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HighlightsLater planting and greater site elevation or latitude decreased seasonal growing degree days and cotton yield in Kansas.Higher irrigation capacity (rate) usually increased lint yield, which was probably due to increased early boll load.Strategies for splitting land allocations between high irrigation rates and dryland did not increase production.Cotton may reduce irrigation withdrawals from the Ogallala aquifer, but the Kansas growing season limits production.Abstract. Precipitation in the western Great Plains averages about 450 mm, varying little with latitude and providing 40% to 80% of potential crop evapotranspiration (ETc). Supplemental irrigation is required to fully meet crop water demand, but the Ogallala or High Plains aquifer is essentially non-recharging south of Nebraska. Pumping water from this aquifer draws down water tables, leading to reduced water availability and deficit irrigation to produce an alternate crop such as cotton (Gossypium hirsutum L.) with a lower peak water demand than corn (Zea mays L.). Our objective was to compare simulated cotton yield response to emergence date, irrigation capacity, and application period at three western Kansas locations (Colby, Tribune, and Garden City) with varying seasonal energy or cumulative growing degree days (CGDD) and compare split center pivot deficit irrigation strategies with a fixed water supply (i.e., where portions of the center pivot land area are managed with different irrigation strategies). We used actual 1961-2000 location weather records with the GOSSYM simulation model to estimate yields of cotton planted into soil at 50% plant-available water for three emergence dates (DOY 145, 152, and 159) and all combinations of irrigation period (0, 4, 6, 8, and 10 weeks beginning at first square) and capacity (2.5, 3.75, and 5.0 mm d-1). Simulated lint yield and its ratio to ETc, or water use efficiency (WUE), consistently decreased with delayed planting (emergence) as location elevation or latitude increased due to effects on growing season CGDD. Depending on location, simulated cotton lint consistently increased (p = 0.05) for scenarios with increasing irrigation capacity, which promoted greater early season boll load, but not for durations exceeding 4 to 6 weeks, probably because later irrigation and fruiting did not complete maturation during the short growing season. Cotton WUE generally increased, with greater yields resulting from earlier emergence and early high-capacity irrigation. We calculated lower WUE where irrigation promoted vigorous growth with added fruiting forms that delayed maturation and reduced the fraction of open bolls. The irrigation strategy of focusing water at higher capacities on a portion of the center pivot in combination with the dryland balance did not increase net yields significantly at any location because the available seasonal energy limited potential crop growth and yield response to irrigation. However, the overall net lint yield was numerically larger for focused irrigation strategies at the southwest Kansas location (Garden City). Based on lint yields simulated under uniform or split center pivot deficit irrigation, we conclude that cotton is poorly suited as an alternative crop for central western and northwestern Kansas because of limited growing season CGDD. Keywords: Cotton, Crop simulation, Deficit irrigation, Evapotranspiration, Irrigation capacity, Split center pivot irrigation, Water use efficiency, Yield limiting factors.

Cotton post-harvest processing research requires moisture content determination for seed cotton, cottonseed, and lint. Methods for determining moisture content have changed and are no longer consistent between laboratories. This research compared standard procedures documented in 1972 and those currently practiced for finding moisture content by oven drying, and quantified the variability. Seed cotton from four modern cultivars (ranging from 9.4% to 36.8% foreign matter), lint, and cottonseed were brought from dry conditions, blended, and then stored for more than 30 days in a controlled environment (21°C, 65% RH) to reach uniform moisture content. Additionally, 150 seed cotton samples were placed in plastic zipper bags and sent by air freight to a distant location and back or stored on-site. Drying baskets (652 cm3) were loaded, in random order, with 25, 35, 50, 71, and 100 g seed cotton or 10, 14, 20, 28, and 40 g lint. Cottonseed was placed in 45 cm3 aluminum cups (10 g) or 800 cm3 aluminum baskets (50 g). Wet weights were determined in the controlled environment. After drying, replicated sets of seed cotton, lint, and cottonseed samples were weighed inside a drying oven and then outside the oven while still hot. Some samples were dried for twice the recommended duration. Sample location in the ovens was tracked. Weighing hot seed cotton samples outside the oven after drying increased apparent moisture content by approximately 0.5% due to air buoyancy; weighing lint samples outside the oven increased apparent moisture content by 1%. Smaller differences in apparent seed cotton moisture content were found when halving or doubling the amount of material in drying baskets or doubling the drying duration. Foreign matter had a minor influence on apparent moisture content. Storage for three days and shipping by air freight in plastic zipper bags did not measurably change the apparent moisture content of seed cotton. Sample location within the drying oven made no difference. Current practices are satisfactory if dry weight location is taken into consideration. Measurement uncertainty has decreased compared to 50 years ago, but the recommended minimum number of samples per treatment was increased slightly for greater statistical power. Keywords: Cotton lint, Cottonseed, Moisture content, Oven drying, Seed cotton.

The quality of upland cotton grown in the Texas Plains, which in good seasons constitutes nearly 40% of all U.S. cotton, has changed radically over the past decade. However, production practices, particularly pertaining to harvesting and ginning, remain largely unchanged, with a predominately stripper-harvested crop. Hence, the necessity to subject the lint to vigorous cleaning at the gin could adversely impact the use value of the cotton in high-value added applications more typically served by picker-harvested cotton. This research was conducted to provide a systemic analysis, combining perspectives from both the gin and the spinning mill, of the impacts of mechanical cleaning on the emerging stripper-harvested cotton with improved fiber properties that appear suitable for ring-spinning. Five cotton varieties grown over three seasons were processed through various sequences of gin and spinning mill cleaning processes. Analysis of the properties of individual fibers across the gin and spinning mill processing chain revealed significant interactions impacting fiber entanglements (neps), mean length, and short fiber content. Both neps and length distribution parameters appeared significantly impacted by fiber damage in both the ginning and spinning processes. However, the damage inflicted through both ginning and spinning may be a function of only fiber maturity. Mature cottons have lower fiber damage potential and appear to be less affected by the processes of lint cleaning and spinning preparation than immature cottons. The latter have higher fiber damage potential, which is reached even with minimal cleaning at the gin because if those immature fibers are preserved at the gin, they will ultimately break in spinning preparation.

Three cottons, one short and coarse, one standard base grade, and one long and fine, were subjected to an experimental lint cleaner with variable working elements (the feed bar, grid bars, and brush) and settings (saw surface speed of 399 m min-1 vs. 612 m min-1, batt density of 100 g m-2 vs. 250 g m-2, and combing ratio of 23 vs. 50). Using a climate-controlled room, the effect of fiber moisture (dry 4.8% vs. optimal 6.2%) on fiber damage across these factors was also measured. The creation of neps and short fiber content (SFC) was greatest at the transfer point between the feed bar and saw, particularly when the saw speed, batt density, and combing ratio were highest, although nep levels were lower for samples with high batt density, a result attributed to the poor grip between the feed roller and feed plate nip for the lighter-weight batt. The long and fine cotton suffered the most damage, i.e., nep and SFC generation increased proportionately more when the saw speed and combing ratio settings were highest. Damage was reduced without affecting trash content by employing combinations of increased fiber moisture, reduced combing ratio and/or batt density, and reduced saw speed. The combination of less aggressive settings was particularly successful in reducing the high number of neps in the long and fine cotton. The nep count in this cotton using optimal moisture, low batt density, low combing ratio, and slow saw speed was 540 neps g-1, as compared with 636 neps g-1 when the more aggressive settings were used. This study provides a basis and direction for future research into the design of better fixed-batt saw lint cleaners.

The management of moisture in cotton during ginning remains one of the most important factors in determining final quality. Resistance plates are typically used to measure moisture in seed-cotton and lint as it is processed through the gin, but these are limited by inaccuracies that arise from the small proportion of cotton tested, contamination of the sensor, and by the non-linear response to low and high moisture levels. In this article, we present a new sensing device that has potential for measuring the moisture of lint while it is being processed in the gin. The device combines large-area capacitance plates with light detectors to measure the mass and moisture of material traveling quickly under pneumatic pressure or gravity through gin ducts. Industrial trials showed significant correlations between moisture values given by the device and values measured off-line. This was despite only a narrow range of moisture contents (4.9% to 6.1%) occurring during the trial period. Further trials are necessary to evaluate the device over a wider range of conditions and to examine its potential to control ginning processes.

Large quantities of seed coat fragments (SCF) in cotton bales cause processing problems for textile plants. Previous research has shown that cotton cultivars differ considerably for the number and weight of SCF in lint. With the recent trend toward cultivars with smaller seed, there has been some concern that increased SCF levels could result from smaller seeds that are more easily damaged or more likely to pass through ginning ribs. Therefore, the objective of this study was to analyze cultivar differences for SCF in lint and determine the relationship with other cultivar traits such as seed index, seed diameter, distribution of seed diameter, and seed linter content. A total of 63 cotton cultivars were planted in Stoneville, Mississippi, in a randomized complete block design in 2004 as part of the Mississippi State Regional Cotton Variety Trial. The cotton was machine harvested and ginned with a typical sequence of gin machinery. Seed coat fragment content ranged from 9.4 to 29.1 SCF g-1 lint among cultivars. Seed index ranged from 7.1 to 10.7 g per 100 seeds, and mean seed diameter ranged from 4.5 to 5.2 mm. Cultivars differed significantly for seed diameter distribution. A polynomial relationship was found between SCF content and seed index, with SCF initially increasing with seed index and leveling off or decreasing with larger seed index. A similar relationship was found between SCF content and seed diameter. No consistent relationship was found between SCF content and seed diameter distribution parameters. The results of this study showed no indication that cultivars with smaller seed, either overall or in the tails of the seed diameter distribution, were prone to higher SCF content.

Cotton stripper harvesters have used extractor-type cleaners for many years to remove large foreign material from seed cotton. These machines are commonly referred to as "field cleaners" and are similar in design and operation to stick machines used in cotton gins. The field cleaners used on modern cotton strippers are capable of processing burr cotton at the harvesting rate of four-row strippers but are overloaded when used on strippers with six- and eight-row headers. The objective of this work is to report on the design and optimization of a new field cleaner with improved cleaning performance and processing capacity. A 0.305 m (1 ft) wide prototype machine was constructed and used in a response surface experiment to optimize cleaning performance and lint loss. Predictive equations were developed using five configuration factors: loading rate per unit width, primary saw cylinder speed, reclaiming saw cylinder speed, primary saw grid spacing, and reclaiming saw grid spacing. As observed in previous work, the results indicate that a balance must be reached in the trade-off between maximizing cleaning performance and minimizing lint loss. The results also indicate that the experimental machine is capable of reaching 60% cleaning efficiency but that additional design modifications and testing are necessary for the machine to reach the lint loss design goal of less than or equal to 1%. Keywords. Cleaning, Cotton, Harvesting, Stripper, Trash. tripping is the predominate cotton harvest method used in the Texas High Plains region. Cotton strip- pers were developed as a cost-effective alternative to picker harvesters for gathering the High Plains crop, which was characterized by relatively low yields (414 to 807 kg ha-1 (0.77 to 1.5 bales ac-1)), short plant heights, and storm-proof boll conformations that held mature seed cotton tightly inside the open burr (the term "burr" refers to the dried carpel segments of the cotton boll). Historically, picker harvesters were much less effective at harvesting the High Plains crop due to the storm-proof nature of the bolls (bolls are the segmented fruit of the cotton plant containing locks of seed cotton) and short plant stature. However, new cultivars with improved yield potential and fiber quality properties are being introduced to the region. Today, it is not

One goal of lint cleaning at a cotton gin is to reduce the non-lint material to an acceptable level with minimal fiber damage. In an effort to improve lint cleaner performance, an initial study was conducted on lint collected before and after lint cleaning at nine commercial gins across the cotton belt to characterize non-lint content. Samples from this study were first processed with an MDTA-3 (Micro Dust and Trash Analyzer 3, SDL Atlas, Stockport, U.K.) to determine trash, fiber fragment, and dust content. The trash portion was retained for additional manual fractionation to determine the percent of material classified as seed coat fragments (SCF), motes, funiculi, sticks, leaf, bark, lint, and "other" material. Leaf, SCF, and sticks were the largest fractions, accounting for 81% of the total trash sample. Overall, total trash decreased by 57% due to lint cleaning, and trash fractions remained consistent in samples before and after lint cleaning. Lint cleaning efficiency in terms of SCF was less than the overall cleaning efficiency, and lint cleaning efficiency for bark, mote, and other (all minor components) was higher than the overall cleaning efficiency. The lint cleaning efficiency for SCF was increased significantly when higher SCF levels were found before the lint cleaner, but this trend was not found for other fractions. Results of this experiment will help direct future studies to improve lint cleaning.

Seed coat fragments (SCF) in lint cause problems in textile mills during spinning and dyeing, so it is important to prevent or remove them during ginning. The objective of this experiment was to quantify SCF as they were formed and removed during ginning so that future studies can focus on preventing SCF formation. Samples of cotton, seed, and trash were collected throughout a gin to analyze SCF, motes, seed meats, and seed. The lint cleaner did not change the number of SCF in lint, but it reduced the weight of SCF by 56% as it removed larger SCF or broke them into smaller SCF. Seed meats in the ginned seed and small seed missing after the gin stand were estimated to be 0.8% and 2.3%, respectively, of all seed ginned, accounting for 32% and 15% of SCF formed in the gin stand, so a significant portion of SCF was attributed to seed damage not revealed by simply observing damaged seed in the seed roll. Damaged seed observed in the seed roll was 7% higher than in seed cotton, and these were thought to be a major source of SCF found in lint. The SCF mass entering the gin stand was 24% of the SCF mass exiting the gin stand, so a small but significant portion of SCF were formed before the gin stand. Seed meats found in the seed cotton cleaner waste were estimated to account for 22% of SCF found entering the gin stand. Seed damage occurred in the field, in seed cotton cleaners, and in the gin stand, so there are opportunities at each of these steps to prevent SCF in lint.

This study included 38 early and 27 medium maturing cultivars planted in Stoneville, Mississippi (2002 and 2003) and Tribbett, Mississippi (2003). About 50% of the cultivars tested in 2002 were repeated in 2003. Variation in gin stand energy consumption was measured as an indicator of differences in fiber-seed bond strength. After subtracting idling energy, the gin stand consumed an average of 20.2 Wh/kg lint with a range of 16.4 to 24.3 Wh/kg lint across cultivars in all tests. Changes in ginning energy were found to correlate with changes in seed linters content, ginning rate, seed percent, and turnout, but ginning energy did not appear to be dependent on these factors. The gin stand energy requirements were lower for cultivars with large seed and low seed linters content. Ginning energy did not change with fiber length, but it increased with short fiber content as more fibers were broken in multiple places. Cultivars that used less energy during ginning tended to have higher HVI fiber strength, so reduced fiber-seed bond strength was not the result of reduced fiber strength. Ginning energy increased with the number of neps, number of seed coat neps, and weight of seed coat fragments, and it decreased with seed cotton cleaner efficiency. This indicated that energy was used to remove tangled fibers and trash. Some properties were found to be closely related to ginning energy, but ginning energy was thought to be independent of these properties. Evidence suggested that cultivar differences in energy consumption at the gin stand were closely related to differences in the fiber-seed bond strength.

The powered roll gin stand has been evaluated in numerous studies evaluating its impact on production and fiber quality properties. The question remained as to what speed the various components of the powered roll gin stand should be operated at to optimize performance. The three main components of the power roll gin stand are the paddle roll, seed finger roll, and gin saw. This article presents results of an optimization study conducted on the second power roll gin stand operating at the USDA-ARS gin lab in Lubbock, Texas. The results are based on lint samples taken after the gin stand (before lint cleaning) and after one stage of lint cleaning, seed samples, and performance data. Of the 14 response variables evaluated, four variables resulted in significant models: seed coat neps, short fiber content, ginning rate, and visible mechanical damage. Several optimal solutions were obtained based on the input factors used in the evaluation. When including all response variables in the analysis, the optimal operational settings for a retrofitted Lummus-116 powered roll gin stand before and after lint cleaning were: paddle roll speed = 209 and 209 rpm, paddle roll loading = 17.1 and 17.0 amps, saw speed = 831 and 829, and seed finger speed = 26 and 21 rpm, respectively. The influence of the various components of the powered roll gin stand on production rate, turnout, and various fiber quality parameters need to be understood to a greater extent so that control systems can be developed to take full advantage of this technology.

The study of the addition of water to cotton at ginning dates back to the early 1950s. Since that time, technologies have changed, allowing for more control and higher volumes of water to be added to cotton at the lint slide than ever before. The objective of this study was to determine an acceptable bale moisture range within which fiber quality, yarn quality, and dyed fabric quality degradation can safely be avoided after six months of bale storage. Approximately 22.7 kg (50 lbs) of cotton were sampled from each of the three bales for each of the four moisture treatments after six months in storage. In addition to the HVI fiber properties, additional testing of the fibers was performed on the Advanced Fiber Information System (AFIS), as well as a microbial assay to determine any microbial damage to the cotton during storage. The resulting 20/1 open-end spun yarns were subjected to typical yarn quality measurements (C.V., defects, strength, and elongation) and then circular-knit into panels so that yarn from each treatment was butt-knit to more easily observe color or shade change. HVI data indicated that the moisture treatment levels and storage period had an adverse impact on color Rd and +b with increasing amounts of water added at the lint slide. Although microbial data were collected, the data did not indicate any significant activity during the six months of storage. As for yarn quality, it appears that 9.1 kg (20 lbs) or more of water added to bales of cotton at the lint slide resulted in significant as well as practical reductions in yarn quality. With respect to the six-month storage period and the treatments used in this study, although there were color changes to the cotton fiber, there appeared to be no impact on the bleached and dyed fabric. Additionally, it appears that the point of diminishing return for adding moisture to cotton at the lint slide lies between 6% and 8.5%.

A subsurface drip irrigation (SDI) system was installed in 2001 in the Coastal Plain of North Carolina. Initially, four zones were installed, each with 0.91 m dripline spacing. In 2002, a fifth zone with 1.82 m dripline spacing was added. This system irrigated a cotton (Gossypium hirsutum L.) and peanut (Arachis hypogea L.) rotation on a Norfolk sandy loam soil. Seed cotton yield data was collected from 2001 to 2004. In addition to SDI, overhead sprinkler irrigation was applied to cotton plots from 2001 to 2003. This study was concurrent with another study that evaluated the effect of irrigation system type, cotton growth regulator (mepiquat chloride), herbicide (glyphosate) treatment, and planting date on lint yield and quality. Although the soil is classified as a sandy loam, water moved laterally to the midpoint of the 1.82 m spaced dripline; this was likely due to the pan layer found at about 0.3 m just below the dripline depth of 0.23 m. There was no difference in lateral water movement between the two dripline spacings. Seed cotton yield and irrigation water use efficiency was not statistically different between irrigation system type or dripline spacing over all years in the study. Seed cotton yield averaged 3.44 Mg ha-1 for the 0.91 m dripline spacing and 3.22 Mg ha-1 for the 1.82 m spacing for the three-year period 2002-2004 compared to an unirrigated average of 2.58 Mg ha-1 for the same period. Average irrigation water use efficiency was greater for the 0.91 m dripline spacing but not statistically different from the 1.82 m spacing. For 2001-2003, when sprinkler-irrigated plots existed, seed cotton yield averaged 3.55 Mg ha-1 for the 0.91 m dripline spacing, 3.35 Mg ha-1 for the sprinkler-irrigated plots, and 2.56 Mg ha-1 for the unirrigated plots. Drought conditions existed in 2002, when 258 mm of rain occurred between planting and final irrigation. The other growing seasons received relatively high amounts of rainfall: 524, 555, and 643 mm in 2001, 2003, and 2004, respectively.